Arapaima gigas

Arapaima gigas is the largest freshwaterfish in the world. You can only keep them in a large showaquarium in a zoo.

Arapaima gigas

Arapaima gigas was first officially described in 1822 by Schinz. The genus name “Arapaima” is derived from the indigenous Tupi language, in which “arapa” means “fish” and “paima” means “leaf”, referring to the fish’s large, scaly scales. The species name “gigas” comes from Latin and means “huge” or “gigantic”, which refers to the enormous size of this fish. In Brazilian Portuguese they are also called Pirarucu. This comes from the local Tupi language and can be roughly translated as “Red Fish”. This is a reference to the caudal fin being colored red.


Arapaima gigas is an impressive fish species with a streamlined body, large fins and a distinctive color. They have a streamlined body with a head that tapers to a copper-green color and an upward mouth. They can reach a length of up to 450 centimeters and a weight of 200 kg. However, more common sizes are approximately 200 centimeters and 100 kg.

The dorsal and anal fins are placed far back. The tail is large and powerful, often with a red color. As mentioned earlier, this is where the local name Pirarucu comes from.

Het lichaam is voornamelijk grijs tot grijs-groen, met rode vlekken op de schubben richting de staart of een roodachtige-oranje kleur van het vlees. The scales are flexible and armor-like, consisting of a hard, mineralized outer layer and a tough but flexible inner layer, which provides protection against piranha attacks.

Sexual Dimorphism

During the breeding period, males acquire a sharp dark coloration on the top of their heads, extending to the back, with yellow spots on the underside of the head and red coloring on the flanks, belly and tail. The color change in females is barely noticeable; the entire body takes on a light brown color.

Differences between Juveniles and Adults

The juvenile stage is characterized by a total length of less than 165 cm and sexual immaturity. Adults reach sexual maturity around the age of five and a length of about 160 centimeters.

Behavior and Temperament

Arapaima gigas is an obligate air breather and must regularly surface to breathe air. They are piscivorous, meaning they eat mainly fish. There is no specific mention of aggressive behavior, but they are mainly solitary.


Arapaima gigas can live up to 15-20 years in the wild. There is no specific data on their lifespan in aquariums, but it is likely that, with proper care, they can achieve a similar lifespan to that in the wild.


The Arapaima gigas inhabits several types of habitats within the Amazon Basin, such as floodplains, lakes, and major tributaries of the Amazon, including the Rio Madeira and the Rio Machado. They live in both white water and clear water, often in oxygen-poor areas such as swampy parts of the rainforest. Their habitat often contains an abundance of plants, especially in the flood plains where seasonal flooding occurs.

The bottom of their habitat is usually sand and mud, especially in the lakes and river channels where they build nests and breed.

Natural enemies

The main natural enemies of the Arapaima gigas are humans, who hunt them for their meat, and caimans such as the spectacled caiman (Caiman crocodilus).


Arapaima gigas are primarily piscivorous, meaning their diet consists mainly of fish. However, they also consume other prey such as birds, reptiles (e.g. small caimans and turtles), and even small mammals. In the wild, they can consume more than 8% of their body weight per day. For a 90 kg fish this means about 7 kg of food per day.

In an aquarium environment, the diet of the Arapaima gigas should mimic their natural diet as much as possible. This can include fish, the most important part of their diet. But also shrimps and crustaceans, pieces of chicken or beef and large insects. Fish should remain the main part of their diet.

Breeding Arapaima gigas

Given the size of this fish species, it is clear that they cannot be bred in a normal living room aquarium.

During the reproductive period, male Arapaima gigas exhibit a striking color change. The males acquire a sharp dark coloration on the top of their heads, extending to the dorsal region, almost to the attachment of the dorsal fin. The underside of the head gets yellow spots, while the flanks, belly and tail get a red color. They usually reproduce during the rainy season.

The Arapaima gigas makes nests on hard ground without vegetation and organic matter. The nests have a diameter of approximately 47 cm and are 15 to 20 cm deep. This usually occurs in shallow waters on the shores of lakes, canals and lagoons. The males guard the eggs and young for about a month. The woman protects the fry and male by patroling around them.

A female Arapaima gigas can lay between 10,000 and 20,000 eggs per clutch. However, not all eggs are fertilized. The eggs are about 2.5 to 3 millimeters in size.



John de Lange

Copyright images

Hung You Chen

Additional information






Sudis gigas, Vastres arapaima, Vastres cuvieri



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